Development of Water Resources in Pakistan

Notes for Cambridge International Examinations

Q. Why is irrigation necessary for growing crops in many areas of Pakistan?

A. In Pakistan, rainfall is highly variable in time and distribution. It is less in quantity. Many areas of Pakistan are arid and semi arid for example Baluchistan and Sindh which is why there is scanty rainfall there. In Karachi there are less than 10 days of rainfall.The monsoon system flows in heavy showers over a short period of time and the land does not absorb it, either because it drains away too quickly or because its evaporation rate is very high. This is why we cant depend on rainwater for irrigation. Agriculture is the backbone of Pakistans economy and we need water for planting the crops which is why irrigation is done in many areas of Pakistan

Q. Why are rivers important for Pakistan?

A. They are a good place of settlement and add to the scenic beauty of an area.

Fishing can also be done on rivers and lakes.

Rivers provide water which can be used for hydroelectric powers in mountainous areas.

It provides water for irrigation which is vital for Pakistans economy.

It provides water which can be used for industrial and domestic purposes.

Q. Why was the Indus Water Treaty necessary for Pakistan?

A. It was necessary because Pakistans economy depends on agriculture which is why we need the rivers for irrigation. If there had been no treaty, India would’ve stopped the flow of water from the headworks of the rivers and there would’ve been food shortages in Pakistan leading to economic crisis and other problems.

Q. Naming an industry in each case, describe three different purposes for which manufacturing and processing industries use water.

A. Pharmaceutical industry:

1. For making syrups

2. For making injections

3. For making drips

Food industry:

1. For making beverages

2. For making juices

3. For making squashes

Textile industry

1. Blueing

2. Dyeing

3. Printing

Q. State the differences between dams and barrages

• Dams are used for hydro electric power making whereas barrages don’t.

• Dams are made in mountaineous terrains, barrages can be made on flat land

• Dams are comparatively more expensive to build, barrages are comparatively cheaper to build.

Q. Explain the differences between:

1. Lined canals and unlined canals

A. Lined canals are man made and are made of cement and they have strong embankments

Unlined canals are naturally made and they have loose embankments

2. Perennial canals and inundation canals

A. Perennial canals supply water throughout the year and cause water logging and salanity

Inundation canals flow only in the summer seasons when the rivers flood and they actually keep a balance between evapo transpiration and rainfall and thus, they do not cause water logging and salanity.

Q. Describe the problems which have resulted from the use of unlined canals to supply water for irrigation in Pakistan?

A. Unlined canals have loose embankments. They do not stop the flow of water seeping underground, so the water drains into the ground thus increasing the water table and causing the twin problems of water logging and salanity making the land unfit for agriculture.

Q. Other than supplying water to industry, for what purposes may reservoirs and dams be used?

A. Dams are important for making hydro electric power. They provide recreation. Dams are important for supplying water for agriculture because the canals are connected to it. Dams are a good source of flood control. Water can be stored up in reservoirs during heavy monsoon rainfalls and this can be later used in times of difficulty for example in times of drought. Dams also provide water for domestic use.

Q. Describe the Persian Wheel method of irrigation.

A. In the Persian wheel method, there is a vertical wheel and buckets/earthenware pots are slung on it and it is turned by a system of cogs. It is powered by a blind folded bullock or an ox which is used to drive a horizontal wheel around in circles. In this way the vertical wheel draws up water from the well and the buckets/earthenware pots unload the water into a channel which takes the water to the fields for irrigation.

Q. What is siltation and what are its causes and effects?

A. Siltation is the deposition of mud and silt in the rivers. Its main cause is erosion. Due to deforestation, the trees are cut down. The trees hold the soil and stop it from being washed by heavy rains. When there are no trees the rains wash down the soil and flow into rivers. Siltation has many negative effects. The silt settles at the bottom and thus it reduces the water storage capacity of a dam, which ultimately means that there is less hydro electric power production. Siltation also blocks canals. It traps the turbines and damages them. It also weakens the foundation of the dams.